wifi: ath12k: Refactor the ath12k_hw get helper function argument

wifi: ath12k: Refactor the ath12k_hw get helper function argument

Currently, ath12k_hw is placed inside the ath12k_hw_group. However, the
ath12k_hw get helper function takes the device handle and the index as
parameters. Here, the index parameter is specific to the group handle.
Therefore, change this helper function argument from the device handle
to the group handle.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1

Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
Acked-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
Acked-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20250112071630.4059410-3-quic_periyasa@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>